Monitoring system, method for the process-parallel monitoring of collision or overload situations in machine tools

ABSTRACT

In a monitoring system for the process-accompanying monitoring or detection of collision or overstress situations in machine tools ( 1 ), comprising a machine control ( 2 ) with one or more sensors ( 4 ) for detecting measured signals or measured signal curves, a monitoring means ( 6 ) in which a comparison of the measured signals or measured signal curves of at least one sensor ( 4 ) with stored monitoring thresholds is performed, and a bidirectional interface ( 8 ) between the monitoring means ( 6 ) and the machine control ( 2 ), it is provided that the monitoring means ( 6 ), apart from detecting collision or overstress situations in a machine tool ( 1 ) and transferring machine stop or machine reaction instructions to the machine control ( 2 ), also permanently stores the measured signals or measured signal curves of the sensors ( 4 ) as measured by the sensors ( 4 ) before, during and after a collision or overstress situation and the data and statuses of the machine control ( 2 ).

The invention relates to a monitoring system as well as to a method for the process-accompanying monitoring of collision or overstress situations by means of event data recorders at machine tools according to the preamble of claims 1 and 5, respectively.

Monitoring systems for the in-process monitoring of collision or overstress situations at machine tools belong to the state of the art and aim at detecting machine collisions in process and stopping the machine drives—first, mostly only the feed drives—as fast as possible to avoid consequential damage.

Such in-process monitoring systems are already provided with an electric interface between the monitoring system and the machine control to monitor, in process, the signal courses of the sensors in monitoring sections predetermined by the machine control and to stop the machine via the same interface if collision or overstress situations or also a tool breakage, for example, is detected. So far, the interfaces between the machine tool control and the monitoring system have been substantially provided in the form of parallel input and output signals for the SPC control. Such a parallel interface between the SPC and a tool and process monitoring or collision and overstress detection system exists, for example, according to the BAPSI standard (Brankamp-Artis-Prometec standard interface) which already allows for the transfer of data words as tool code or cutting code from the NC program to the monitoring system.

A known control Sinumerik 840 D of the Siemens company comprises a so-called tachograph which, however, is only able to log operational processes. It is not started by a measured or detected collision or overstress event, but simply logs all operational processes, resulting in the disadvantage that other reasons for machine damage caused by collision are not detected.

It is the object of the invention to provide a monitoring system as well as a method for the in-process monitoring of collision or overstress situations at machine tools, which, in case of a collision or overstress situation, not only intervenes into the machine control but moreover permits a later judgment of the causes of such a collision and overstress situation.

This object is solved by the features of claims 1 and 5, respectively.

According to the invention, the object is solved by an in-process monitoring system for the process-accompanying monitoring or detection of collision or overstress situations, comprising a large permanent memory forming an event data recorder, e.g., a flash disc, and preferably a field bus interface between the machine control and the monitoring system, in connection with a data transfer between the electric interface of the machine control and the monitoring system as well as in connection with a sensor signal supplying collision-relevant measured signals.

This means that the solution according to the invention provides the documentation of collision or overstress situations at machine tools by an event data recorder in order to securely detect the causes of such collision and overstress situations in case of them occurring.

The invention is able to use the field bus interfaces (beside or instead of the parallel interfaces) only recently offered by the control manufacturers, which permit to perform a more extensive exchange of information between the machine control that consists of the stored program control (SPC) or the NC control.

Such a system for documenting collision or overstress situations at machine tools by an event data recorder in order to securely detect the causes of such collision and overstress situations in case of them occurring has not been known yet.

In case of a collision or overstress situation, it has not been possible, according to prior art, to later detect the causes that have led to the situation. Since the economic damage by machine shut-down or machine damage may be considerable in these cases, the detection whether technical or human failure was the cause is of considerable economic importance.

Furthermore, the detection of the cause permits to detect defects in the machine components, in the operational process or mistakes of operating persons and avoid them in the future.

The monitoring system for the process-accompanying monitoring and detection of collision or overstress situations among machine components or of tools with machine components or workpieces or of workpieces with machine components or tools in machine tools at least consists of

-   -   one or more sensors for detecting measured signals or measured         signal curves as may be produced at collisions, overstresses or         damage to machine tools, which are to be equated with at least         one direction of force, a resultant force, a pressure, a torque,         a motor output, a motor current, even if it is taken from the         values of the motor current sensor of the control, a vibration,         an acceleration, a distance variation or a structure-borne         noise,     -   a monitoring means consisting of monitoring hardware with         software, wherein a comparison of the measured signals or         measured signal curves of at least one sensor with stored         monitoring thresholds is made by monitoring and evaluating         strategies of a known and random type, such as static         thresholds, dynamic thresholds, thresholds of signal pattern         curves etc. with the aim to give a corresponding report from the         monitoring system to the machine control in order to immediately         stop the machine tool or at least its feed drives, and     -   a bidirectional interface between the monitoring hardware and         the machine control (consisting of the SPC and the NC control),         which effects a data exchange between the machine and the         monitoring system and is adapted, e.g., to activate the         monitoring system via a signal as soon as a feed slide moves and         even to transfer spindle-, tool- or even cutting specific         monitoring sections in the form of data words as different         numbers or instructions from the NC or SPC program to the         monitoring system for the purpose of dividing the monitoring         into different monitoring sections, and is also adapted to         transmit machine stop or at least machine reaction instructions         to the machine control at the moment of detecting collisions or         overstress situations.

Optionally, an operating means consisting of an operating hardware with software for operating and/or parameterizing the monitoring system and/or for visualizing the measured signals may be provided.

Apart from detecting collision or overstress situations in a machine tool and transferring machine stop or machine reaction instructions to the machine control, this monitoring system is also capable of permanently storing the measured signal data records (measured signals or measured signal curves) of the sensors as measured by the sensors before, during and after a collision or overstress situation as well as the data and statuses of the machine control that are of interest as to the detection of the causes of a collision or overstress situation.

The measured signal data records of the sensors in the working storage of the monitoring system are continuously logged. Only at the detection of the collision or overstress are the measured data transferred into the permanent memory of the monitoring system.

The monitoring system continuously logs at least one measured signal data record (measured signal or a measured signal curve) of each of the sensors into the working storage.

Preferably, the monitoring system continuously logs two measured signal data records of each of the sensors into different working storage locations with respectively different resolutions as to time, referred to as “long” and “short”. This means that one measured data record is stored in a small time window with high resolution and one measured data record is stored in a larger time window with lower resolution.

Upon detecting the collision or overstress situation, the measured signal data records are immediately transferred into the permanent storage locations of the monitoring system and thus to the machine control together with the report of this situation.

The measured data records (measured signals or measured signal curves) to be filed in the permanent memory location and having the “long” resolution as to time preferably start about 2 seconds before the collision or overstress situation and end about 3 seconds thereafter.

The measured data records to be filed in the permanent memory location and having the “short” resolution as to time preferably start about 100 milliseconds before the collision or overstress situation and end about 150 milliseconds thereafter.

Immediately with the report of a collision or overstress situation from the monitoring system to the machine control, the latter begins, by means of an appropriate software, to detect data and statuses of the machine control that are of interest as to the detection of the causes of a collision or overstress situation and to transfer them to the monitoring system via the interface between the machine control and the monitoring system in order to write into the permanent memory thereof, which serves as an event data recorder, by means of the software of the monitoring system.

Preferably, the interface between the machine control and the monitoring system is a field bus interface, such as, for example, a process data highway or an interbus (as bidirectional interface).

At least one of the following data records and/or status parameters of the machine control is written into the permanent memory of the monitoring system with respect to the detection of the causes of a collision or overstress situation:

-   -   program name or number that has been active in the NC control     -   record number where the NC program has been stopped by the         monitoring system     -   present tool number in the form of the T or D number     -   operational mode of the machine (setting, jog, automatic)     -   programmed tool correction values from the tool correction         memory     -   programmed zero point displacement     -   setting of the override switch for feed     -   setting of the override switch for spindle speed     -   speed of the spindles     -   programmed speed of the feed slides     -   present speed of the feed slides     -   programmed feed of the feed slides     -   position or actual position values of the feed slides     -   date and time

Immediately with the report of a collision or overstress situation from the monitoring system to the machine control, the monitoring system is able to write all states of the signals of the bidirectional interface between the monitoring system and the machine control, such as those according to the BAPSI standard, into the permanent memory thereof.

Immediately with the report of a collision or overstress situation from the monitoring system to the machine control, all monitoring-relevant data of the monitoring means, such as, for example, the position of the monitoring thresholds, the measuring ranges and gain degrees of the sensors, the characteristic values for filtering the measured signals, the monitoring mode such as teach-in, setting etc., can be written in the permanent memory thereof.

All the measured signal curves, signals, data and statuses to be stored in the permanent memory of the monitoring system with respect to a detected collision or overstress situation belong to an unmistakable and marked data record.

All the measured signal curves, signals, data and statuses of a data record concerning a collision or overstress situation can be displayed and, if necessary, printed out by means of the operating means (operating hardware and software) for operating and/or parameterizing the monitoring system and/or visualizing the measured signals.

Hereinafter, an embodiment of the invention is explained in detail with reference to the only drawing:

The monitoring system for the process-accompanying monitoring or detection of a collision or an overstress situation in a machine tool 1 with a machine control 2 shown in the drawing comprises at least one or more sensors 4 for detecting measured signal data records. The measured signal data records are supplied to a monitoring means 6 in which a comparison of the measured signal data records of at least one sensor 4 with stored monitoring thresholds is performed for detecting collision or overstress situations. In case of the measured signal data records violating the monitoring thresholds, the monitoring means 6 supplies a set of instructions to the machine control 2 in order to immediately stop the machine tool 1 or at least its feed drives 3.

The machine control is composed of a stored program control SPC for the machine tool 1 and a NC control for the drives 3. According to prior art, it is possible to bidirectionally exchange data and statuses between the stored program control SPC and the NC control.

Between the monitoring means 6 and the machine control 2, a bidirectional interface 8 is provided, effecting a data exchange between the machine tool 1 and the monitoring means 6.

The monitoring means 6 comprises a working memory 12 into which the monitoring means 6 continuously writes at least one measured signal data record of each of the sensors 4; in this connection, it is also possible that several measured signal data records of each of the sensors 4 are continuously written into different working memory locations of the working memory 12 with a respectively different resolution in time.

Apart from detecting collision or overstress situations in a machine tool 1 and transferring machine stop or machine reaction instructions to the machine control 2, the monitoring means 6 is also capable of storing the measured signal data records of the sensors 4 as measured by the sensors before, during and after a collision or overstress situation as well as the data and statuses of the machine control 2 in an event data recorder 14 consisting of a permanent storage, e.g., a flash disc.

Furthermore, the monitoring means 6 may be connected to an operating means 10. All measured signal curves, signals, data and statuses of a data record concerning a collision or overstress situation can be displayed and, if necessary, documented by printout by the operating means 10 for operating and/or parameterizing the monitoring system and/or visualizing the measured signal data records. 

1. The monitoring system for the process-accompanying monitoring or detection of collision or overstress situations in machine tools (1), comprising a machine control (2), one or more sensors (4) for detecting measured signal data records, a monitoring means (6) in which a comparison of the measured signal data records of at least one sensor with stored monitoring thresholds is performed, and a bidirectional interface (8) between the monitoring means (6) and the machine control (2). characterized in that the monitoring means (6), apart from detecting collision or overstress situations in a machine tool (1) and transferring machine stop or machine reaction instructions to the machine control (2), also permanently stores the measured signal data records of the sensors (4) as measured by the sensors (4) before, during and after a collision or overstress situation and the data and statuses of the machine control (2).
 2. Monitoring system according to claim 1, characterized in that the monitoring means (6) comprises a permanent memory serving as an event data recorder (14).
 3. Monitoring system according to claim 1, characterized in that the system comprises one or more sensors (4) for detecting measured signal data records (measured signals or measured signal curves) as produced at collisions, overstress or damage to machine tools (1), which are to be equated with at least one direction of force, a resultant force, a pressure, a torque, a motor output, a motor current, even if it is taken from the values of the motor current sensor of the control, a vibration, an acceleration, a distance variation or a structure-borne noise, a monitoring means (6) in which a comparison of the measured signal data records of at least one sensor (4) with stored monitoring thresholds, such as static thresholds, dynamic thresholds, thresholds of signal pattern curves is made with the aim to give a corresponding report from the monitoring system (6) to the machine control (2) in order to immediately stop the machine tool or at least its feed drives (3) in case of measured signal data records violating the monitoring thresholds, and a bidirectional interface (8) between the monitoring means (6) and the machine control (2) , which effects a data exchange between the machine (1) and the monitoring system (6) and is adapted to activate the monitoring means (6) via a signal as soon as a feed slide moves or to transfer spindle-, tool- or cutting specific monitoring sections in the form of data words from the NC or SPC program to the monitoring means (6) for the purpose of dividing the monitoring into different monitoring sections, and is also adapted to transmit machine stop or at least machine reaction instructions to the machine control (2) at the moment of detecting collisions or overstress situations.
 4. The monitoring system according to claim 1, characterized in that the monitoring means (6) is connected to an operating means (10) for operating and/or parameterizing the monitoring system and/or for visualizing the measured signals.
 5. Method for the process-accompanying monitoring or detection of collision or overstress situations in machine tools (1) with a monitoring system according claim 1, characterized in that the measured signal data records of the sensors (4) are continuously logged in a working memory (12) of the monitoring means (6) and that the measured signals or measured signal curves are only transferred to an event data recorder (14) of the monitoring means (6) when a collision or overstress is detected.
 6. Method according to claim 5, characterized in that the monitoring means (6) continuously logs at least one measured signal data record of each of the sensors (4) into a working memory (12).
 7. Method according to claim 5 claim 5, characterized in that preferably, the monitoring means (6) continuously logs two measured signal data records of each of the sensors (4) into different working memory locations of the working memory (12) with a mutually different resolution in time.
 8. Method according to claim 5, characterized in that the transfer of the measured signal data into the event data recorder (14) of the monitoring system is immediately effected at the detection of the collision or overstress situation and thus together with the report of this situation to the machine control (2).
 9. Method according to claim 7, characterized in that the measured signal data records to be filed in the event data recorder (14) and having the lower resolution preferably start about 2 seconds before the collision or overstress situation and end about 3 seconds thereafter.
 10. Method according to claim 7, characterized in that the measured signal data records to be filed in the event data recorder (14) and having the higher resolution preferably start about 100 milliseconds before the collision or overstress situation and end about 150 milliseconds thereafter.
 11. Method according to claim 5, characterized in that the machine control (2) immediately begins to detect data and statuses of the machine control (2) and to transfer them to the monitoring means (6) via the interface (4) between the machine control (2) and the monitoring means (6) and to write them into the event data recorder (14) thereof when a collision or overstress situation of the monitoring system is reported to the machine control (2).
 12. Method according to claim 11, characterized in that the interface (8) between the machine control (2) and the monitoring means (6) preferably is a field bus interface such as, for example, a process data highway or an interbus.
 13. Method according to claim 11, characterized in that at least one of the following data and statuses of the machine control (2) is written into the event data recorder (14) of the monitoring means (6) in case of a collision or overstress situation: program name or number that has been active in the NC control, record number where the NC program has been stopped by the monitoring system, present tool number, operational mode of the machine, programmed tool correction values from the tool correction memory, programmed zero point displacement, setting of the override switch for feed, setting of the override switch for spindle speed, speed of the spindles, programmed speed of the feed slides, present speed of the feed slides, programmed feed of the feed slides, position or actual position value of the feed slides, date and time.
 14. Method according to claim 5, characterized in that immediately with the report of a collision or overstress situation from the monitoring means (6) to the machine control (2), all statuses of the signals of the bidirectional interface (8) between the monitoring means and the machine control (2) are also written into the event data recorder (14) by the monitoring means (6).
 15. Method according to claim 5, characterized in that immediately with the report of a collision or overstress situation from the monitoring means (6) to the machine control (2), all monitoring-relevant data of the monitoring means (6), such as, for example, the position of the monitoring thresholds, the measuring ranges or gain degrees of the sensors (4), the characteristic values for filtering the measured signals, the monitoring mode such as teach-in or setting are also written into the event data recorder (14).
 16. Method according to claim 5, characterized in that all measured signal curves, signals, data and statuses to be filed in the event data recorder (14) of the monitoring means (6) with respect to a detected collision or overstress situation belong to an unmistakable and marked data record.
 17. Method according to claim 5, characterized in that all measured signal curves, signals, data and statuses of a data record concerning a collision or overstress situation can be displayed and, if necessary, printed out by the operating means (10) for operating and/or parameterizing the monitoring system and/or for visualizing the measured signals.
 18. Monitoring system according to claim 2, characterized in that the system comprises one or more sensors (4) for detecting measured signal data records (measured signals or measured signal curves) as produced at collisions, overstress or damage to machine tools (1), which are to be equated with at least one direction of force, a resultant force, a pressure, a torque, a motor output, a motor current, even if it is taken from the values of the motor current sensor of the control, a vibration, an acceleration, a distance variation or a structure- borne noise, a monitoring means (6) in which a comparison of the measured signal data records of at least one sensor (4) with stored monitoring thresholds, such as static thresholds, dynamic thresholds, thresholds of signal pattern curves is made with the aim to give a corresponding report from the monitoring system (6) to the machine control (2) in order to immediately stop the machine tool or at least its feed drives (3) in case of measured signal data records violating the monitoring thresholds, and a bidirectional interface (8) between the monitoring means (6) and the machine control (2) , which effects a data exchange between the machine (1) and the monitoring system (6) and is adapted to activate the monitoring means (6) via a signal as soon as a feed slide moves or to transfer spindle-, tool- or cutting specific monitoring sections in the form of data words from the NC or SPC program to the monitoring means (6) for the purpose of dividing the monitoring into different monitoring sections, and is also adapted to transmit machine stop or at least machine reaction instructions to the machine control (2) at the moment of detecting collisions or overstress situations.
 19. Method according to claim 6, characterized in that preferably, the monitoring means (6) continuously logs two measured signal data records of each of the sensors (4) into different working memory locations of the working memory (12) with a mutually different resolution in time.
 20. Method according to claim 8, characterized in that the measured signal data records to be filed in the event data recorder (14) and having the lower resolution preferably start about 2 seconds before the collision or overstress situation and end about 3 seconds thereafter.
 21. Method according to claim 12, characterized in that at least one of the following data and statuses of the machine control (2) is written into the event data recorder (14) of the monitoring means (6) in case of a collision or overstress situation: program name or number that has been active in the NC control, record number where the NC program has been stopped by the monitoring system, present tool number, operational mode of the machine, programmed tool correction values from the tool correction memory, programmed zero point displacement, setting of the override switch for feed, setting of the override switch for spindle speed, speed of the spindles, programmed speed of the feed slides, present speed of the feed slides, programmed feed of the feed slides, position or actual position value of the feed slides, date and time. 